Prostaglandins play a major role in the inflammation process and the inhibition of prostaglandin production, especially production of PGG.sub.2, PGH.sub.2 and PGE.sub.2, has been a common target of anti-inflammatory drug discovery. However, common non-steroidal anti-inflammatory drugs (NSAIDs) that are active in reducing the prostaglandin-induced pain and swelling associated with the inflammation process are also active in affecting other prostaglandin-regulated processes not associated with the inflammation process. Thus, use of high doses of most common NSAIDs can produce severe side effects, including increased gastric acid levels and life threatening ulcers, that limit their therapeutic potential. A popular current alternative to NSAIDs is the use of corticosteroids, which have even more drastic side effects, especially when long term therapy is involved.
1,2-Diarylcycloalkenes have been made and used for a variety of utilities. For example, U.S. Pat. No. 4,543,207 to Sato, et al., describes diphenyl cyclohexene as an electrical insulating oil additive. U.S. Pat. No. 4,229,207, to Laanio, et al., describes 1,2-diphenylcyclohex-1-ene-4-carboxylic acid esters, specifically, 1,2-di(4-phenylsulfonic acid)-cyclohex-1-ene-4-carboxylic acid ethyl ester. These ester compounds are reported to be effective as plant growth regulating agents and as post-emergent herbicides for controlling wild oats.
The synthesis of 3,4-diphenyl-.DELTA..sup.3 -cyclopentenone ethylene ketal is described as an intermediate for forming carbinols [E. J. Corey, et al., J. Amer. Chem., Soc., 85, 1788-1792 (1963)]. 2,3-Bis-(4-hydroxyphenyl)-2-cyclopenten-1-one has been identified from the knot resin powder of Arqaucaria angustifolia [H. Ohash, et al., Phytochemistry, 31, 1371-73 (1992)].
Substituted 1,2 -diphenylcyclopentenes have been synthesized for use in studies of their rotational behavior, includes specifically, 1-(2,4-Dimethylphenyl)-2-phenylcyclopentene [D. Y. Curtin, et al., J. Org. Chem., 36, 565-72 (1971)]. 1,2-Di-(2'-methoxyphenyl)-.DELTA..sup.1 -cyclopentene has been identified as an impurity in the synthesis of cannabinoids [O. P. Malik, et al., Ind. J. Chem., 14B, 975-78 (1976)].
1-(Substitutedphenyl)-2-phenylcyclopentenes have been synthesized to study their photochemical reactions into phenanthrene derivatives. Compounds with meta substituents, such as 1-(3-chlorophenyl)-2-phenylcyclopentene, are described in Somers, et al., J. Photochem. Photobiol., 48A, 353-74 (1989). Para substituents, including specifically 1-(4-fluorophenyl)-2-phenylcyclopentene, are described in Laarhoven, Pure & Appl. Chem., 56, 1225-40 (1984).